<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      div {
        position: absolute;
        left: 0px;
        width: 200px;
        height: 200px;
        background-color: blue;
      }
    </style>
  </head>
  <body>
    <div></div>
    <script>
      var div = document.querySelector("div");
      var timer = setInterval(function () {
        if (div.offsetLeft >= 400) {
          clearInterval(timer);
        }
        div.style.left = div.offsetLeft + 1 + "px";
      }, 10);
    </script>
  </body>
</html>
